Their curiosity is expressed, not only in their eyes, but in their movements. They share with mankind the desire to touch what is novel to them. A diver was approached by a large catfish, who came up and touched him with its cold nose. The man involuntarily threw up his hand, and struck the palm on the fish's sharp fin. There was an instant struggle before the fish wrenched itself free, and then it only swam off a short distance, staring with its black eyes at the intruder as if it wished to ask who he was, and what he wanted.
A long stay by the diver in a single place enables him to test the intelligence of the fishes who visit him. A diver, whose occupation kept him in one spot, was continually surrounded, while at work, by a school of gropers, averaging about a foot in length. Having identified one of them who had suffered from an accident, he noticed that it was a daily visitor. After they had satisfied their first curiosity, the gropers apparently decided that their novel visitor was harmless and clumsy, but useful in assisting them to get their food. They feed on crustacea and marine worms, which hide under the rocks, on mosses, and other objects on the bottom. In raising anything from the mud a dozen of these fish would thrust their heads into the hole for their food, before the diver had removed his hand. They followed him about, eying his motions, dashing in advance, or around in sport, and evidently displaying a liking for their new friend. Pleased with such unexpected familiarity, the diver brought food with him, on his return, and fed them from his hand as one feeds a flock of chickens. Sometimes two would get hold of the same morsel, and then would result a trial of strength, accompanied with much flashing and glitter of shining scales. But no matter how called off, their interest and curiosity remained with the diver. They would return, pushing their noses about him, with an apparent desire to caress him, and bob down into the treasures of worm and shell fish his labor disclosed. He became convinced that they were sportive, and indulged in play for the fun of it. This curious intimacy was continued for weeks: that they knew and expected the diver at his usual hour, was a conclusion he could not deny, since they, unless driven away by some other fish who preyed on them, were always in regular attendance during his hours of work.
The depth at which men can descend in a suit of submarine armor, has been tested by experiment with the following results: The diver can breathe, and his organs may retain their normal condition, and he preserve his presence of mind, to a depth of 130 feet, but when he exceeds this depth by ten or twenty feet, the external pressure causes physiological effects on his organs, independent of his will. One hundred and thirty feet is therefore the depth which experiment has shown to be the greatest at which any prolonged submarine work can be performed. Within this limit, security to life is perfectly compatible with an attempt to recover any ship or sunken treasure which will pay the expenses.
THE NORTHERN DIVER.
STAR FISH.